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P.A. Feldman, R.O. Redman (NRC/Canada), S.J. Carey (BC), M.P. Egan (AFRL)
We present polarimetric observations of the thermal emission from dust in the filamentary parts of Infrared-Dark Clouds (IRDCs) identified during the MSX mid-infrared survey of the Galactic Plane. In 1999 September we observed 3 IRDC filaments at 850~\mum with the SCUBA polarimeter on the JCMT. The observed percentage polarizations are quite high (~~6%), and the directions of the inferred magnetic fields are correlated with the structures in the clouds. The field structures appear to be complex, but in general we find a trend for the magnetic fields to be aligned along the directions of the filaments. Bright, compact sources in the filaments are much less strongly polarized, and their inferred magnetic field directions are generally perpendicular to the orientation of the filaments. The IRDCs we observed appear to be composed of well-ordered, magnetized filaments containing protostars at all stages of development. Some of the massive condensations within these filaments appear to be quiescent, with no obvious embedded protostars. These condensations provide opportunities to study magnetic field structures in clouds prior to the onset of star formation.
The author(s) of this abstract have provided an email address for comments about the abstract: Paul.Feldman@nrc.ca